I set up a part containing a PathfindingModifier so that pathfinding compute will avoid this part. You can see in the video the pathfinding avoids walking through the part at the section with the BasePlate below it, but then walks through it when SmoothTerrain is there.
It should avoid the whole part, even if the ground is SmoothTerrain.
Pf Repro.rbxl (84.2 KB)